Coal has been used as an electric power generation fuel, and the attention on the power generation method therewith is transferred from a pulverized coal combustion boiler power generation, which is an ordinary method, to an integrated coal gasification combined cycle (IGCC) power generation facility, which has good efficiency and is excellent in environmental conservation. In an integrated, coal gasification combined cycle (IGCC) power generation facility, coal as a fuel is gasified for operating a gas turbine, and electric power generation is performed by utilizing the driving power of the gas turbine and the waste heat from the gas turbine. Accordingly, gasification techniques for converting coal to gas have been actively developed in various fields (see, for example, PTL 1 and PTL 2).
On using coal as an electric power generation fuel, finely pulverized coal is introduced firstly to a pyrolysis furnace. In the pyrolysis furnace, coal is pyrolyzed by mixing with a high temperature gas generated in a high temperature gas generation furnace, and thereby a pyrolyzed gas, an oil and a char are formed as pyrolyzed products. The char thus formed is separated from the gas and the oil with a cyclone. The whole or a part of the char thus separated is gasified (partial oxidation) with oxygen gas in a high temperature gas generation furnace (gasification furnace) and thus is converted to a high temperature gas (which contains hydrogen and carbon monoxide as major components). The high temperature gas is then introduced to a water gas shift reaction furnace, and carbon monoxide is converted to hydrogen and carbon dioxide by a water gas shift reaction according to the following scheme (1). Furthermore, carbon dioxide is removed from the reaction gas, and thus a fuel gas rich in hydrogen is generated.CO+H2O=CO2+H2  (1)
In the gasification furnace and the water gas shift reaction furnace for purifying the fuel gas (H2) for the gas turbine, the fuel gas after the reaction contains hydrogen (H2) and also the equimolar amount of carbon dioxide (CO2).
The fuel gas containing carbon dioxide (CO2) has been ordinarily fed to the gas turbine in some cases, but in recent years, carbon dioxide (CO2) is removed by an absorption process in most cases. Such a separation membrane is also proposed that can be utilized for removing carbon dioxide contained in the gas after reaction (see, for example, PTL 3).